1. Field of the Invention
The present invention relates to a position encoded sensing device (PESD) and a method of sensing a position with respect to a display device. In particular, the present invention relates to a liquid crystal display sensing device having a position encoded light guide plate, together with a transceiver for emitting light to the light guide plate and receiving light reflected from the light guide plate, such that the present invention senses or determines the precise position of the transceiver with respect to the display, based on the encoded information disposed within the light guide plate.
2. Related Art
Flat panel displays have become very popular in the electronic industry. Flat panel displays are generally provided in electronic products such as notebook computers, desktop monitors, televisions, digital cameras, DVD players, PDAs, mobile phones, portable games, and car navigation systems, among other applications. Some flat panel displays are position sensible liquid crystal display (PSLCD) devices whereby the PSLCD can sense the position of a stylus only when the stylus is in a direct contact with the display panel.
For instance, FIG. 1 shows an LCD with an electromagnetic digitizer. FIG. 1 illustrates a flat panel display 10 having a cover and protective glass layer 11, an LCD layer 12, and an electromagnetic digitizer layer 13. The electromagnetic digitizer layer 13 contains a sensor board 15 made up wires in a grid format. The electromagnetic digitizer layer 13 is disposed at the bottom layer of the flat screen display 10. The flat screen display 10 of FIG. 1 is pressure sensitive such that the stylus 14 must be in a direct contact with the display 10. Pressure must be applied onto and detected by the sensor board of the electromagnetic digitizer layer 13 of the display 10 in order for the display 10 to sense the position of the stylus. The display 10 as shown in FIG. 2 is a complicated structure since the sensor board 15 contains a complicated grid of wires.
FIG. 2 shows another example of a PSLCD 20 having an integrated resistive touch sensor disposed therewith. The PSLCD 20 includes an LCD 21 and a polarizing filter 22. Moreover, the PSLCD 20 includes a flexible conductive layer 23 disposed on the polarizing filter 22. A stylus 24 is provided to make direct physical contact with the flexible conductive layer 23 of the PSLCD 20. In order for the PSLCD 20 to sense the position of the stylus 24, the flexible conductive layer 23 must sense the resistive touch applied by the stylus 24 on the display. Since the flexible conductive layer 23 is disposed on the polarizing filter 22 of the PSLCD 20 of FIG. 2, a substantial amount of processing is made on the polarizing filter 23. As such, the transparency of the display is significantly decreased.
In addition, FIG. 3 shows another example of a PSLCD device 30 which includes a LCD 31 and a stylus 32. In addition, the PSLCD device 30 includes a plurality of detecting units 33 disposed on two corners of the LCD 31. The PSLCD device 30 of FIG. 3 is a pressure sensitive device such that the stylus 32 must make physical contact with the LCD 31 in order for the PSLCD device 30 to function. Specifically, pressure must be applied to the LCD 31 from the stylus, and the detecting units 33 must detect the stylus and the applied pressure in order for the PSLCD device 30 to function properly. Given the configuration as shown in FIG. 3, the PSLCD device 30 contains numerous disadvantages. For example, the PSLCD device 30 requires a plurality of detecting units 33 mounted on the corners of the LCD 31 which causes the device to be ergonomically awkward and cumbersome. Moreover, the detecting units 33 increase the weight of the device. Also, the functional accuracy of the PSCLD device 30 is easily diminished by extraneous light and particles that comes into contact with the PSLCD device 30, and in particular in contact with the detecting units 33.
In view of the aforementioned PSLCD devices with their disadvantages, there is a need to have a flat screen display device that can employ a liquid crystal display sensing device having a position encoded light guide plate (LGP), together with a transceiver so that the display device can have a simplified module structure without requiring additional control circuitries. Moreover, there is also a need as well as market demand for a position encoded liquid crystal display sensing device that can be thinner in size and lighter in weight.